Convergence properties of blind algorithms for base station CDMA receivers

In this paper, the blind estimation of wireless CDMA receiver coefficients from the second order statistics of the signals is considered. Although many algorithms have been proposed so far, their performance analysis has always been carried out assuming perfect receiver coefficients estimation and/or under time-invariant conditions. In this article, we present some decision-directed blind algorithms and use a time-varying vector channel simulator to compare their performance with those of many previously proposed algorithms. It is shown that decision-directed chip-level algorithms can operate without the use of training sequences to avoid catastrophic error propagation, and that one should not expect an increase in performance from using least squares instead of least-mean-square. Furthermore the unpracticability of the bit-level algorithm (Gerlach 1992) and of the least significant algorithm (Liu and Zoltowski 1997) under a time varying environment is outlined. The performance of the principal component (Stanford) algorithm (Naguib and Paulraj 1995) is also studied.